1. Field of the Invention
The invention relates to a bidirectional semiconductor switch in the field of power electronics.
2. Discussion of Background
Such a bidirectional semiconductor switch has already been described in German Offenlegungsschrift DE 4,011,509.
In recent years, modern converter concepts have been presented in the field of power electronics for industrial drives (see in this connection, for example, T.A. Lipo, IEEE Transactions on Power Electronics, Vol. 13, No. 2. April 1988, pages 105-117). However, the realisation of these converter circuits (for example, of the matrix converters mentioned in the article by Lipo) requires components which have a bidirectional conductivity and blocking ability. The application of such components, which can be switched on and off in two directions, renders it possible to save the otherwise necessary freewheeling diode and largely to dispense with protective elements.
In the abovementioned Swiss patent (CH 1491/89-8), the bidirectional switching function is achieved by a subassembly which has control electrodes on the front and on the rear. This is a thyristor with bilateral, MOS-controlled short circuits, which guarantee the bidirectional blocking ability and conductivity.
However, a component which has control electrodes on both sides not only places high demands on the production process, but in addition the cooling and the integration of the subassembly into a housing are problematical. Such components are therefore also very expensive.